package com.atguigu.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Arrays;

/**
 * Scattering 将数据写入到buffer时，可以采用buffer数组依次写入
 * Gathering 从buffer读取数据时，可以采用buffer数组依次读取
 */
public class ScatteringAndGatheringTest {
    public static void main(String[] args) throws IOException {
        //使用ServerSocketChannel 和 SocketChannel 进行通信
        ServerSocketChannel serverSocketChannel=ServerSocketChannel.open();
        InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);

        //绑定端口到socket，并启动
        serverSocketChannel.bind(inetSocketAddress);

        //创建buffer数组
        ByteBuffer[] byteBuffers=new ByteBuffer[2];
        byteBuffers[0]=ByteBuffer.allocate(5);
        byteBuffers[1]=ByteBuffer.allocate(3);

        //等待客户端连接
        SocketChannel socketChannel = serverSocketChannel.accept();
        int messageLength=8;
        //循环读取
        while (true){
            int byteRead=0;
            while (byteRead<messageLength) {
                long l = socketChannel.read(byteBuffers);
                byteRead += l;
                System.out.println("byteRead="+byteRead);
                //使用流打印，看看当前这个buffer的position和limit
                Arrays.asList(byteBuffers).stream().map(buffer->{
                    return "position="+buffer.position()+" limit="+buffer.limit();
                }).forEach(System.out::println);
            }

            //将所有的buffer进行反转
            Arrays.asList(byteBuffers).forEach(buffer->buffer.flip());
            //将数据读出显示到客户端
            long byteWrite=0;
            while(byteWrite<messageLength){
                long l=socketChannel.write(byteBuffers);
                byteWrite+=l;
            }

            //将所有的buffer进行清空
            Arrays.asList(byteBuffers).forEach(buffer->buffer.clear());
            System.out.println("byteRead:="+byteRead+" byteWrite="+byteWrite+" messageLength="+messageLength);
        }
    }
}
